Hulk and Abom are the only "mutant" type creatures on MCU earth, so it's not like Tony has come across lots of people with powers.

It's just wierd that Tony meets a guy who can fly, summon lightning, crush part of his armor, and not be astounded.

OR Thor and Loki simply grew up at a normal rate and still did the things it says they did in the myths. Asgardians are extremely long lived but who's to say it takes them centuries to reach adult hood, they might reach adulthood around the same speed as humans.

Bingo. Bingo. Bingo.

The whole cycle of ragnarok would probably be a bit confusing to casual viewers, as I have tried to explain it to my friends. We know thor is over 1000 years old, even in the MCU. I assume everything written about them, has indeed happened.

Opposed to Ragnarok being a cycle, I feel it is just a prophecy, the destruction of all the nine realms. Period.